A communication hub typically connects multiple nodes in communication network such as a local area network (LAN). By connecting the nodes in the network to the communication hub via communications links (e.g. coaxial, twisted-pair, or fiber optic cable), the communication hub relays data packets from the various nodes along the appropriate data path in the communications network. This allows the various communication nodes to communicate with one another. However, the data packets received by the communication hub are usually deteriorated to an unacceptable level. This requires the communication hub to restore the signal quality of the data packets and to tack on any truncated portions of the data packets before transmitting the data packets to another node. Typically, the original signal quality and the truncated portion of the data packet are restored by regenerating the signal.
If the communication hub fails to restore the original signal quality to an acceptable level, to tack on any missing portions, or to transmit the data packets along the appropriate data path, the communication network may not function properly (i.e. transmit incorrect data packets). Although most communication hubs are presently tested during production to ensure that the communication hubs manufactured meets the required performance and quality specifications, it is desirable to test the communication hubs while operating in the field. For example, if there is a breakdown in a communication network system, it is desirable to test the communication hub in its normal working environment without removing the communication hub from the network.
In an Ethernet network, a typical Ethernet frame or packet includes a preamble, a header, data, and trailer components or sequences. When an Ethernet communication hub, such as an Ethernet repeater, receives a packet of data, a portion, if not the entire preamble sequence may be truncated. Typically, the preamble sequence precedes the data portion of the packet, and as the receiver is synchronizing the incoming signals, the preamble sequence is truncated. Therefore, the Ethernet communication hub usually regenerates the specified preamble sequence and combines the regenerated preamble sequence with the original header, data and trailer components before transmitting the data packet to the rest of the nodes in the network.
Presently, Ethernet repeaters are tested during manufacturing by connecting the Ethernet repeater to an external tester. The external tester may be a test system manufactured by Netcom located in Los Angeles, Calif., multiple personal computers or some other tester that is capable of individually stimulating each of the transceivers in the repeater. The Ethernet repeaters are usually tested by individually stimulating each of the transceiver ports and then checking the test packets that are transmitted by the other transceiver ports. A transceiver port is stimulated when it receives a test packet from the external tester. FIG. 1 illustrates a test set-up for testing an Ethernet repeater with an external test system. Typically, this set-up is used during the production testing of the Ethernet repeater or during the evaluation of the Ethernet repeater at some other test facility (i.e. a failure analysis laboratory). In other words, the Ethernet repeater may only be tested at locations which are suitable for this test set-up.
An Ethernet repeater typically includes multiple transceivers for interfacing with other communication nodes through a transmission medium (such as a twisted pair cable). The transceivers usually include circuitry for both the transmission and the reception of data packets. Furthermore, an Ethernet repeater typically includes core logic for coordinating the data traffic for the transceivers. One of the functions of the core logic is to detect a collision when two or more data packets simultaneously receive a data packet.
The tester 120 shown in FIG. 1, externally stimulates the transceiver 140 by sending test packets to the transceiver 140 over an external connector 150. The external connector 150 may be a cable. The test packets received by the repeater 110 flow through the transceiver 140 and over line 160 to the receive port 170 of the repeater core logic 130. From the receive port 170, the test packets flow through the repeater core logic 130 and out through the transmit port 171 of the repeater core logic 130 onto line 161. Line 161 is coupled to the transceivers 141, 142 and 143. From line 161, the test packets are transmitted by the transceivers 141, 142 and 143 to the tester 120 to be tested.
Therefore, according to FIG. 1, the receiving channel of the transceiver 140, the repeater core logic 130 and the transmitting channels of the transceivers 141, 142 and 143 are tested when the transceiver 140 is externally stimulated. Similarly, the receiving channels of the transceivers 141, 142 and 143 may be individually stimulated by the tester 120. By transmitting the test packets through a selected path within the Ethernet repeater, a selected portion of the Ethernet repeater is tested.
One of the drawbacks of testing the Ethernet repeater in the manner shown in FIG. 1 is that expensive testing equipment is typically required. Another drawback is that it is very difficult to implement this test set-up out in the field. For all practical purposes, this test set-up is typically limited to a production/manufacturing facility or a testing facility because of the physical connections required for this set-up. For example, in order to test all of the transceiver ports, the tester must be physically connected to the back of every transceiver port.
Therefore, it is desirable to provide an apparatus and method of testing Ethernet repeaters without the added costs associated with external test equipment. Furthermore, it is desirable to have the flexibility of testing the Ethernet repeater at various locations.